An Unsuspected Intraventricular Schwannoma

Intraventricular schwannomas are rarely encountered in neurosurgical practice. The development and progression of a schwannoma within the ventricular system is still a hypothesised theory. Here, we present a case of a 59-year-old female who presented with a three-week history of headaches. Her symptoms progressively worsened, with resultant altered mental status within the last week. Imaging scans of the brain demonstrated a well-defined mass within the right lateral ventricle with associated midline shift and obstructive hydrocephalus. A parietal craniotomy and resection of the intraventricular mass was performed. Her postoperative course was uneventful. Histopathological assessment depicted a biphasic pattern of Antoni A and B, with a strongly positive S100. This was in keeping with an intraventricular schwannoma. The diagnosis of an intraventricular schwannoma does not fit within the classical differential framework for ventricular masses. These tumours are extremely uncommon but fortunately, they are typically benign. Therefore, adequate surgical resection remains the gold standard of care for these unfamiliar masses.

Multiple intracranial juvenile xanthogranuloma not a straightforward diagnosis (a case report)

INTRODUCTION AND IMPORTANCE

Juvenile xanthogranuloma (JXG) rarely presents as multifocal intracranial disease in the paediatric population. Therefore, this case of extensive tumour burden, primarily within the lateral ventricles, presented a neurosurgical challenge on numerous fronts.

PRESENTATION OF CASE

This is the case of a 9-year-old male presenting with a 2-year history of visual disturbances. Radiographic imaging demonstrated extensive intracranial masses involving both lateral ventricles, the straight sinus and right cerebellum. A staged tumour resection was planned, targeting the lesions within the right lateral ventricle initially. Complete resection was achieved during surgery. Post-operative morbidity showed a decline in the patient's functional status with respect to mobility and communication, Glasgow outcome scale 3. Extensive immunohistochemical analysis ultimately revealed a diagnosis of JXG. The patient is undergoing chemotherapy, with subsequent surgical resection being dependent on overall recovery.

CLINICAL DISCUSSION

JXG is the most common form of non-Langerhans histiocytosis and typically arises as a cutaneous disorder during early childhood. It is a rare cause of extensive intracranial tumour burden, with limited publications of this kind in the literature. This is even more atypical given the absence of any of the classic cutaneous morphology seen in JXG.

CONCLUSION

JXG involving the central nervous system is a rare encounter. Therefore, a clear algorithm for the management of a case of extensive intracranial tumours resulting from JXG has not been defined. This only amplifies the difficulty in treating these cases.

The relationship of the multi-shell to multistage and standard median filters

It is shown that for a particular window size, by changing gradually the minimum and maximum operators to the higher and lower order statistics of the shell, respectively, the multi-shell median filter will gradually turn from a multistage max/median filter into a 2-D standard median filter.

Identification of a single amino acid residue in the capsid protein VP1 of coxsackievirus B4 that determines the virulent phenotype

To identify the molecular determinants of virulence for coxsackievirus B4, a panel of recombinant, chimeric viruses were constructed from cDNA clones of a virulent virus, CB4-V, and a nonvirulent virus, CB4-P. Initial studies mapped a major determinant of virulence to the 5' end of the viral genome, which contained the 5' untranslated and the P1 regions (A. Ramsingh, A. Hixson, B. Duceman, and J. Slack, J. Virol. 64:3078-3081, 1990). To determine whether the 5' untranslated region contributed to the virulent phenotype, a chimeric virus (vCB403) containing this region of the virulent virus on an avirulent background was tested in mice. The vCB403 construct displayed a phenotype similar to that of CB4-P, suggesting that the 5' untranslated region did not significantly contribute to virulence. Analysis of the sequence data of the P1 regions of both CB4-V and CB4-P revealed five mutations that resulted in amino acid substitutions in VP1, VP2, and VP4 (A. Ramsingh, H. Araki, S. Bryant, and A. Hixson, Virus Res. 23:281-292, 1992). Analysis of individual mutations in both VP1 and VP2 revealed that a single residue (Thr-129 of VP1) determined the virulent phenotype.

Identification of candidate sequences that determine virulence in Coxsackievirus B4

We have previously shown that a major determinant of virulence for coxsackievirus B4 mapped to the 5' end of the viral genome. Comparison of the corresponding cDNA sequences of a virulent and a non-virulent virus has allowed the identification of candidate determinants of virulence in the 5' untranslated region and the capsid proteins VP1, VP2 and VP4. Thirteen nucleotide substitutions were observed in a region spanning 3298 nucleotides. Four mutations were detected in the non-coding region. Of the remaining nine mutations, four were silent while five resulted in amino acid substitutions in VP1, VP2 and VP4. The amino acid substitutions in the virulent virus were analyzed in relation to the three-dimensional structures of the capsid proteins of poliovirus. Two substitutions mapped to the amino termini of VP1 and VP4. Of the two substitutions observed in VP2, one mapped to the large loop that connects beta strand E with the radial helix on the back surface of the eight-stranded antiparallel beta barrel while the other mapped to beta strand G. One amino acid substitution in VP1 mapped to the loop connecting beta strands D and E at a site close to a major determinant of attenuation in poliovirus type 2.

Evidence suggesting that virulence maps to the P1 region of the coxsackievirus B4 genome

A chimeric virus containing the P1 region of a virulent variant of coxsackievirus B4 and the P2 and P3 regions of a nonvirulent strain was constructed from cDNA clones. The chimeric virus induced pancreatitis with concurrent hypoglycemia similar to that observed in mice infected with the virulent variant.

Severity of disease induced by a pancreatropic Coxsackie B4 virus correlates with the H-2Kq locus of the major histocompatibility complex

Coxsackie B viruses are known etiological agents of pancreatic diseases, including diabetes. The pathogenesis of these infections is influenced by both host and viral factors. In this report, we examined whether the outcome of Coxsackie B4 virus infection is dependent on the genes within the major histocompatibility complex (MHC). We generated a pancreatic variant, CB4-V and established an animal model system of pancreatitis with concurrent hypoglycemia in mice. Infection of various B10 H-2 congenic strains of mice revealed that the development of hypoglycemia with accompanying pancreatitis was independent of the MHC haplotype. However, the severity of the disease as monitored by the extent and duration of hypoglycemia and by mortality rate was found to be associated with the H-2 haplotype, specifically the H-2Kq locus. Pancreatic damage induced by CB4-V appeared to be both immune-mediated and viral-mediated. Histological examination of pancreatic tissue from infected B10 H-2 congenic mice revealed an association between acute destruction of the exocrine pancreas and lymphocytic infiltration. This infiltration may correlate with immune-mediated destruction of the infected pancreatic tissue. Since preferential replication of CB4-V was not observed in the most susceptible B10 mouse strain, direct viral destruction may not be the major mechanism of pancreatic injury.

Genetics and expression of the Q6 and Q8 genes. An LTR-like sequence in the 3' untranslated region

A unique 2.2-kb mRNA is transcribed from the Q6 and Q8 genes of the mouse major histocompatibility complex. RNase protection experiments and DNA sequence analysis have mapped the 3' terminus to a site located 1110 bp downstream from exon 8. Comparison of the 3' sequence of Q8 to that of Q7 revealed that the two genes diverge from one another at a point located 200 bp into the untranslated domain. This finding explains the increased size of the transcript. RNase protection experiments involving twelve different strains of mice have revealed few sequence polymorphisms. A tissue distribution of the 2.2-kb transcript in B6 mice revealed that the highest quantities of message were present in the spleen with decreasingly lower amounts in the thymus, liver, kidney, testis, and brain. The H-2r haplotype appeared novel; it is phenotypically Qa-2-, yet expressed a 2.2-kb transcript which hybridizes to a Q8 probe. A comparison of a Qa-2hi expressor, B6, and a Qa-2low expressor, BALB/cFla, has established that these quantitative cell surface differences are reflected in mRNA differences. A homology search of the Genbank database has revealed that the 3' portion of Q8 contains extensive homology to a retrovirus-like long terminal repeat sequence that is characteristic of an embryonic-specific transposon (ETn).

Pichinde virus L and S RNAs contain unique sequences

Using oligodeoxyribonucleotides produced by limited DNase I digestion of calf thymus DNA as a primer, we synthesized complementary DNA (cDNA) from the L and the S RNAs of Pichinde virus. The reaction conditions for in vitro cDNA synthesis were optimized to allow transcription of about 90% of either L or S RNA. No significant hybridization was observed when the L cDNA was hybridized to the S RNA, or when the S cDNA was hybridized to the L RNA. The results indicate that the L and S RNAs of Pichinde virus contain unique nucleotide sequences.